MONTPELIER — A bill approved by the Senate that would prohibit a public school from closing and reopening as an independent school contains an amendment calling for a study to determine if such a law would be constitutional.

With a unanimous voice vote Friday morning, the Senate approved a bill that would prevent a town from “flipping” its school, meaning closing a school only to have it reopen and serve essentially the same population. It also calls for the Agency of Education to determine if towns have the constitutional authority to flip a school.

However, Sen. Joseph Benning, a Republican from Caledonia County, offered an amendment that calls for a study to determine if the Legislature has the authority to impose such a moratorium in the first place.

“If we’re going to have a study to determine whether or not towns have the constitutional authority to flip a school, then surely we ought to have, in conjunction with that, a study that determines if the state has the constitutional authority to prevent such an activity from happening,” Benning said.

The amendment was approved and became part of the bill.

The Senate bill as approved is the product of a pair of amendments and, in the end, bears little resemblance to the bill as originally introduced. The original bill, S.91, titled “An act relating to public funding of some approved independent schools,” contained language that would have imposed standards that independent schools would have to meet in order to receive money from the state.

Those standards would have included a requirement that the schools have a “blind admissions” policy, meaning they could not deny education to a student who requires special education services.

Other provisions would have required the schools to offer free lunch to students who qualify economically and would prohibit a school from denying enrollment based on a student’s race, creed, color, national origin, marital status, sex, sexual orientation, gender identity or disability.

Some independent schools in Vermont receive public funding. During the 2013 fiscal year, 2,525 of the state’s approximately 90,000 students attended independent schools, at a total cost of $36.7 million.

However, on Thursday, the Senate approved an amendment to the bill that struck all of those requirements and instead inserted language to prohibit public schools from closing and reopening as independent schools that would serve the same student population.

There have been several instances of public schools closing and immediately reopening as independent schools, including most recently the North Bennington Graded School in 2013.